code: def unregisterCallback(fn):
      """Unregister a previously registered callback."""
      callbacks.remove(fn)
  
file_path: pyqtgraph/pyqtgraph/exceptionHandling.py
imports: import sys
  import threading
  import time
  import traceback
  from types import SimpleNamespace
label_desc: Use image node_id 2 for calling a global function with example usage: unregisterCallback(fn) without return types